FVIII is synthesized as a single chain precursor of approximately 280 kD with the domain structure of A1-A2-B-A3-C1-C2 and it circulates as a series of metal ion-linked heterodimers that result from cleavages at B-A3 junction as well as additional cleavages within B domain. Factor VIII is converted to its active form, factor VIIIa, upon proteolytic cleavages by thrombin and is a heterotrimer composed of the A1, A2, and A3-C1-C2 subunits. A1 subunits of factor VIIIa terminates with 36 residue segment (Met337-Arg372) rich in acidic residues. This segment is removed after cleavages at Arg336 by activated protein C, which results in inactivation of the cofactor. In the present study, site-directed mutagenesis of FVIII at Arg336 to Gln336 was performed in order to produce an inactivation resistant mutant rFVIII (rFVIIIm) with an extended physiological stability. A recombinant mutant heavy chain of FVIII (rFVIII-Hm; Arg336 to Gln336) and wild-type light chain of FVIII (rFVIII-L) were expressed in Baculovirus-insect cell (Sf9) system, and a biologically active recombinant mutant FVIII (rFVIIIm) was reconstituted from rFVIII-Hm and rFVIII-L in the FVIII-depleted human plasma containing 40 mM CaCl2. The rFVIIIm exhibited cofactor activity of FVIIIa (2.85 x 10(-2) units/mg protein) that sustained the high level activity during in vitro incubation at 37 degrees C for 24 h, while the cofactor activity of normal plasma was declined steadily for the period. These results indicate that rFVIIIm (Arg336 to Gln336) expressed in Baculovirus-insect cell system is inactivation resistant in the plasma coagulation milieu and may be useful for the treatment of hemophilia A.
Animal ; Baculoviridae/genetics ; Blotting, Western ; Cell Line ; Factor VIII/metabolism* ; Factor VIII/genetics ; Factor VIII/chemistry ; Factor VIII/biosynthesis ; Genetic Vectors ; Human ; Mutagenesis, Site-Directed ; Recombinant Proteins/metabolism ; Recombinant Proteins/genetics ; Recombinant Proteins/chemistry ; Recombinant Proteins/biosynthesis ; Spodoptera

The study was to explore the change of coagulation factor VIII and IX activities in the platelet suspension collected by platelet apheresis during storage at 22 degrees C. 18 samples of platelet concentrates were collected by the cs-3000 plus and stored at 22 degrees C and then FVIII: C, FIX: C activities were detected at 0, 12, 24, 48, 72, 96, 120 hours respectively by SYSMEX CA-1500. The results showed that FVIII: C activity was (100.51 + 44.02)% at 0 hour, and then decreased dramatically to 10% - 40% of primary level from 12 to 120 hours, while FIX: C activity was (120.93 +/- 20.50)% at 0 hour and decreased to 10% - 35% of primary level from 24 to 120 hours. In conclusion, FVIII and FIX in the platelet concentrates stored at 22 degrees C could keep their biological activities at physiologically high levels.
Blood Platelets ; Blood Preservation ; methods ; Factor IX ; metabolism ; Factor VIII ; metabolism ; Humans ; Platelet Transfusion ; Plateletpheresis ; methods

Adolescent ; Adult ; Child ; Factor VIII ; genetics ; metabolism ; Hemophilia A ; blood ; diagnosis ; Humans ; Male ; Young Adult

OBJECTIVETo construct a recombinant lentiviral vector (pXZ208-BDDhFVIII) mediating B-domain-deleted human coagulation factor VIII (BDDhFVIII) gene and investigate its expression in HLF, Chang-Liver and MSC cells.

METHODSBDDhFVIII gene fragment was separated by endonuclease digestion and was cloned into the multiple cloning sites of pXZ208 to construct a recombinant lentiviral vector pXZ208-BDDhFVIII. Viral particles were prepared by means of three-plasmid cotransfection of 293T package cells by calcium phosphate precipitation. After infection, the coagulant activity of human FVIII in the culture medium of 293T, HLF, Chang-Liver and MSC cells was assayed by one-stage method. The gene transduction efficiency was assayed by flow cytometry (FCM). Furthermore, PCR was performed to test the integration of BDDhFVIII.

RESULTSThe infection rates of HLF, Chang-Liver and MSC were (74.52 +/- 7.57)%, (27.24 +/- 6.53)% and (42.34 +/- 5.84)% respectively. The activities of FVIII in supernatants of HLF, Chang-Liver and MSC were (54.1 +/- 5.6)%, (22.5 +/- 2.9)% and (12.5 +/- 2.7)% respectively. BDDhFVIII gene integration was detected in all the infected cells.

CONCLUSIONThe recombinant lentiviral vector pXZ208-BDDhFVIII was successfully constructed and efficiently integrated into target cells to express human FVIII activity in vitro.

Cell Line ; Factor VIII ; biosynthesis ; genetics ; metabolism ; Gene Expression ; Genetic Vectors ; Humans ; Lentivirus ; genetics ; Plasmids ; Transfection

Coagulation factor VIII (fVIII) is a secretion protein and plays a crucial role in the coagulation cascade. Hemophilia A resulted from deficiency of fVIII is the most common X-linked recessive bleeding disorder. Gene therapy is recognized as an attractive strategy for the eventual cure of this disease. However, the gene therapy is hampered by the big size of fVIII gene when using the most promising gene vectors, adeno-associated virus (AAV) vectors. In this study we explored the intein-mediated protein trans-splicing to deliver a Phe(309)-->Ser mutant full-length fVIII (F309SfVIII) gene by using a dual-vector system. An intein is a protein sequence embedded within a precursor protein and can excise itself through protein splicing. The F309SfVIII is proven to be beneficial to its secretion. The F309SfVIII gene was broken into heavy and light chains before Ser(1239) in B domain and fused with the coding sequences of Ssp DnaB intein respectively to construct a pair of plasmid vectors by inserting them into the pcDNA3.1 vectors. Forty-eight hours after co- or separate transfection of 293 cells, the co-transfected cell lysate showed an obvious ligated F309SfVIII protein band by Western blot with a polyclonal antibody against fVIII. The amounts of secreted F309SfVIII protein in culture supernatants and their bioactivities were (71+/-9) ng/mL and (0.38+/-0.09) IU/mL determined by ELISA and Coatest assay respectively. The supernatant from combined cells with separate transfections also displayed lower levels of F309SfVIII antigen and fVIII activity [(25+/-6) ng/mL and (0.12+/-0.05) IU/mL], indicating the F309SfVIII could be formed by splicing both before and after secretion. The content of F309SfVIII heavy chain protein from co-transfected cell supernatant was higher than that of intein-fused heavy chain transfection alone [(135+/-10) ng/mL vs (37+/-7) ng/mL, P<0.01)]. These data demonstrated that intein could be used as a technical strategy in a dual-vector system delivering F309SfVIII gene with improved secretion of fVIII providing an alternative approach to circumvent the packaging limitation of AAV for F309SfVIII gene transfer, which encourages our continuing study in hemophilia A gene therapy in vivo.
Cell Line ; Dependovirus ; Factor VIII ; metabolism ; Genetic Vectors ; Humans ; Inteins ; Protein Splicing

Conventional therapies for hemophilia A (HA) are prophylactic or on-demand intravenous FVIII infusions. However, they are expensive and inconvenient to perform. Thus, better strategies for HA treatment must be developed. In this study, a recombinant FVIII cDNA encoding a human/rat hybrid FVIII with an enhanced procoagulant potential for adeno-associated virus (AAV)-delivered gene therapy was developed. Plasmids containing human FVIII heavy chain (hHC), human light chain (hLC), and rat light chain (rLC) were transfected into cells and hydrodynamically injected into HA mice. Purified AAV viruses were intravenously injected into HA mice at two doses. Results showed that the hHC + rLC protein had a higher activity than the hHC + hLC protein at comparable expression levels. The specific activity of hHC + rLC was about 4- to 8-fold higher than that of their counterparts. Hydrodynamic injection experiments obtained consistent results. Notably, the HA mice undergoing the AAV-delivered hHC + rLC treatment exhibited a visibly higher activity than those treated with hHC + hLC, and the therapeutic effects lasted for up to 40 weeks. In conclusion, the application of the hybrid FVIII (hHC + rLC) via an AAV-delivered gene therapy substantially improved the hemorrhagic diathesis of the HA mice. These data might be of help to the development of optimized FVIII expression cassette for HA gene therapy.
Animals ; Dependovirus/genetics* ; Factor VIII/metabolism* ; Genetic Therapy/methods* ; Hemophilia A/therapy* ; Humans ; Mice ; Rats

Actins ; metabolism ; Angiomyolipoma ; metabolism ; pathology ; surgery ; Epiglottis ; Factor VIII ; metabolism ; Humans ; Laryngeal Neoplasms ; metabolism ; pathology ; surgery ; Male ; Middle Aged

This study was aimed to construct a lentiviral vector carrying human coagulant factor VIII (FVIII) and to investigate its expression in 293T cells. B-domain-deleted factor VIII gene fragment (BDDhFVIIIcDNA) was obtained by enzyme digestion and cloned into lentiviral vector pXZ208 to establish the expression vector pXZ208-BDDhFVIII. Recombinant viral particles were prepared by cotransfection with packaging plasmid delta NRF and envelope plasmid VSV-G using calcium phosphate precipitation method. 293T cells were transfected by viral supernatant. Coagulant activity of FVIII, BDDhFVIIImRNA and genome integration were assayed by one-step method, RT-PCR and PCR after transfection. The results showed that 293T cells could be transfected by recombinant virus. The transfection rate of 293T was 59.57%. After transfection, the cells expressed FVIII efficiently. Detection confirmed that the activity of FVIII was 12%, 43% and 87% respectively at 24, 48 and 72 hours after infection. BDDhFVIII transcription was detected by RT-PCR from the infected cells. The gene integration in the targeted cells was also observed. It is concluded that the successfully constructed lentiviral vector is able to generate high level expression of human FVIII in 293T cells, which may provide a potential application of gene therapy to haemophilia A.
Cell Line ; Factor VIII ; genetics ; metabolism ; Gene Expression ; Genetic Vectors ; Humans ; Lentivirus ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism

OBJECTIVESTo study the expression of CD34, CD31, CD14, CD10 and factor VIII on blood island of yolk sac (YS), PAS/aorta-germen-mesonephros (AGM) region and hepatic hematopoietic foci.

METHODSThirty-two cases of 3rd-12th weeks human embryo were obtained by drug abortion. Paraffin embedded sections with H.E staining and immunohistochemistry reaction (SABC) were performed.

RESULTSYS blood island of 3rd-4th weeks of gestation was consisted of two types of cells. One was vascular endothelial cells located outside and the other hematopoietic cells inside the blood island. Both the two types of cells were CD10, CD14, CD31 and factor VIII positive. Hematopoietic cells were CD34 negative, and vascular endothelial cells were CD34 positive. On 32nd days of gestation, the hematopoietic cells migrated out of YS. On 4th week of gestation, CD34, CD14, CD10, CD31 and factor VIII positive cells appeared in the aorta, mesonephros and hepatic hematopoietic foci. By the 7th week, the number of positive hematopoietic cells reached the peak. In 11th-12th weeks, most cells in these regions were matured red blood cells and were negative for all the antibodies mentioned above excepting for CD34. During 4th-12th weeks, all endothelial cells in embryo were CD34 positive.

CONCLUSIONSThe hematopoietic cells and endothelial cells of YS blood island co-expressed CD10, CD14, CD31 and factor VIII. Endothelial cells were CD34 positive but hematopoietic cells were negative in YS blood island. The hematopoietic cells of aorta, mesonephros and hepatic hematopoietic foci expressed CD34, CD10, CD14 and factor VIII from 4th week to 7th week. Anti-CD34 antibody could label endothelial cells of every kinds vessels of embryo from 3rd to 12th weeks.

Antigens, CD34 ; metabolism ; Factor VIII ; metabolism ; Fetus ; metabolism ; Humans ; In Vitro Techniques ; Lipopolysaccharide Receptors ; metabolism ; Liver ; metabolism ; Neprilysin ; metabolism ; Platelet Endothelial Cell Adhesion Molecule-1 ; metabolism ; Yolk Sac ; metabolism

OBJECTIVETo develop a monoclonal antibody (mAb) directed to FVIII C2 domain and investigate its effect on FVIII activity.

METHODSFVIII C2 protein was expressed in E. coli and purified. A murine antihuman FVIII C2 domain mAb SZ-132 was developed by standard hybridoma technology and characterized. In coagulation assays, different concentrations of SZ-132 were incubated with freshly collected pooled human plasma and the residual activity of FVIII and activated partial thromboplastin time (APTT) were determined. The effects of SZ-132 on rhFVIII binding to purified human vWF, phosphatidylserine (PS) and platelets were assessed by enzyme linked immunosorbent assays (ELISA).

RESULTSSZ-132 could inhibit FVIII procoagulant activity in a dose-dependent manner within the concentrations of 0-25 microg/ml and the FVIII activity was completely inhibited on above 25 microg/ml. It could also prevent rhFVIII from binding to vWF, PS and platelets.

CONCLUSIONSSZ-132 is a neutralizing mAb against FVIII C2 domain and can inhibit FVIII procoagulant activity by preventing FVIII from binding to vWF and PS.

Animals ; Antibodies, Monoclonal ; biosynthesis ; immunology ; Antibodies, Neutralizing ; biosynthesis ; immunology ; Factor VIII ; immunology ; metabolism ; Humans ; Male ; Mice ; Mice, Inbred BALB C